JP2001342450A - Adhesive and electronic parts using the same - Google Patents

Abstract

(57) Abstract: A wiring conductor cannot be formed on a surface of an adhesive layer for a wiring board constituting an electronic component, because a rough surface that firmly adheres to the wiring conductor layer cannot be formed. Peeling of the layer occurs. An adhesive for an adhesive layer (5) formed on an insulating substrate (4) and having a wiring conductor layer (6) adhered to the surface thereof, comprising an aromatic / heterocyclic resin modified product and a radical polymerizable resin. A cross-linking material, a thermoplastic resin having a weight average molecular weight of 10,000 to 500,000 and dissolved in a roughening liquid, an elastomer having a glass transition temperature Tg of -60 to -20 ° C, and a filler,
The elongation at break after curing is 3 to 10%. According to the adhesive of the present invention, a good rough surface can be formed on the surface of the adhesive layer 5, and the adhesion strength of the wiring conductor layer 6 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive for forming an adhesive layer on a surface of which a wiring conductor layer is adhered, and an electronic component using the same. The present invention relates to an adhesive for forming an adhesive layer having excellent adhesion strength, and a high reliability electronic component having excellent high frequency characteristics and heat resistance using the same.

[0002]

2. Description of the Related Art A wiring board provided with an insulating substrate containing an organic resin as a main component has been known as a wiring board capable of high-density wiring. As such a wiring board, from the viewpoint of ensuring mechanical strength and matching thermal expansion with a wiring conductor, for example, an epoxy resin having heat resistance or chemical resistance as a reinforcing material such as glass fiber or aramid fiber is used. An adhesive made of a thermosetting resin, such as an epoxy resin, is applied to an insulating substrate that is impregnated with a thermosetting resin represented by a composite to form an adhesive layer, and the adhesive layer is cured by heating. After that, a through-hole is drilled in the adhesive layer with a laser, and then the surface of the adhesive layer is chemically roughened, and a conductor layer is formed inside the through-hole by electroless copper plating. 2. Description of the Related Art There is known a wiring board manufactured by a build-up method in which a conductor layer is formed and patterned, and finally, a wiring pattern is adhered and formed by electrolytic copper plating.

[0003] However, such a wiring board is excellent in mechanical strength and heat resistance, but has a high dielectric constant ε of about 3.5 of a thermosetting resin such as an epoxy resin contained in an insulating substrate or an adhesive. For this reason, the dielectric loss is large at the time of signal transmission, and it has a drawback that it cannot be used as a wiring board used in a high-frequency region where high-speed signal processing is required.

On the other hand, fluororesins and cross-linked polyethylene have been used as resin materials for wiring boards used in the high-frequency region, but these have a low glass transition temperature Tg of -100 ° C. or lower. There is a drawback that the dielectric constant and the dielectric loss change greatly depending on the use environment conditions such as temperature and humidity.

In order to improve such dielectric properties, polyethers having a low dielectric constant, a relatively high glass transition temperature Tg, and stable dielectric properties irrespective of the use environment are used as resin materials for wiring boards. Various modified resins such as sulfone, polyetherimide, polyphenylene oxide, polysulfone, norbornene, etc. have been developed, but since these are all thermoplastic resins, the disadvantage is that they are inferior in heat resistance such as solder heat resistance as they are. was there.

Therefore, in order to eliminate the drawbacks in the heat resistance characteristics, modified polyphenylene ether, modified polystyrene and modified norbornene having a rigid molecular structure and having a double bond capable of radical polymerization with a low dielectric constant in the molecular chain. Radical polymerizable cross-linking agent is mixed with the modified aromatic / heterocyclic resin to increase the cross-linking density, or the radiation-crosslinkability of thermoplastic norbornene resin with high glass transition temperature Tg and excellent dielectric properties Radiation is applied to a resin composition to which a good resin / radiation crosslinking aid has been added to cause a crosslinking reaction to increase the crosslinking density, and the aromatic / heterocyclic resin modified product and thermoplastic norbornene resin have excellent properties. There has been proposed an adhesive for a wiring board having improved heat resistance without impairing high-frequency characteristics.

Aromatic / heterocyclic resin modified products such as modified polyphenylene ether, modified polystyrene and modified norbornene, and resins obtained by radiation crosslinking of thermoplastic norbornene resin are all low in dielectric constant and excellent in heat resistance. Also, the crosslinking density is high and the chemical resistance is extremely excellent.

[0008]

However, in the case of a wiring board which requires fine high-density wiring manufactured by the build-up method, the adhesion between the surface of the adhesive layer and the wiring conductor layer is improved. In order to obtain high reliability such as good thermal fatigue resistance and durability, the surface of the adhesive layer is roughened using a roughening solution consisting of an oxidizing agent. Roughness Rma measured with a height measuring instrument
Although x is roughened to about 0.5 to 10 μm, the adhesive layer formed of the above-mentioned modified aromatic / heterocyclic resin or a resin obtained by radiation-crosslinking a thermoplastic norbornene resin has a chemical resistance. It is difficult to dissolve the surface of the adhesive layer formed of these resins by the chemical roughening method, and sufficient adhesive strength with the wiring conductor layer can be obtained on the surface of the adhesive layer. A rough surface cannot be formed. As a result, peeling of a wiring conductor layer occurs in a reliability test such as a temperature cycle test (TCT) or a pressure cooker test (PCT), and the reliability of electrical connection is reduced. There is a problem that application to a high-density wiring board or the like is difficult.

A resin obtained by radiation-crosslinking a modified aromatic / heterocyclic resin or a thermoplastic norbornene resin is inferior in flexibility to less than 3% in elongation at break because the resin skeleton is rigid and has a high crosslinking density. There was also a problem that it was not able to withstand distortion due to thermal expansion and thermal shrinkage when performing TCT, which is a general reliability test, and cracks were easily generated.

Further, conventionally, the surface roughness of the adhesive layer has been measured by a stylus type surface roughness measuring instrument. However, this measuring instrument greatly affects the adhesion between the adhesive layer and the wiring conductor layer.
It is not possible to accurately measure minute irregularities less than μm,
There was also a problem that the peel strength of the wiring conductor layer could not be accurately controlled.

The present invention has been devised in view of the problems of the prior art, and has as its object to provide an adhesive for forming an adhesive layer having excellent adhesion to a wiring conductor layer of a wiring board, An object of the present invention is to provide an electronic component having excellent durability and high-frequency characteristics in reliability tests such as TCT and PCT manufactured using an adhesive.

[0012]

The adhesive of the present invention comprises a modified aromatic / heterocyclic resin, a radically polymerizable cross-linking agent, a weight average molecular weight of 10,000 to 500,000, and is dissolved in a roughening solution. And a glass transition temperature Tg of -60 to
It comprises an elastomer at −20 ° C. and a filler, and has an elongation at break of 3 to 10% after curing.

Further, the electronic component of the present invention comprises: an insulating substrate;
An adhesive layer formed on the insulating substrate using the above adhesive, a plurality of wiring conductor layers formed on each surface of the insulating substrate and the adhesive layer, and a through hole formed in the adhesive layer; An electronic component in which an electronic element is mounted on a wiring board that is formed inside and has a through conductor that electrically connects a plurality of wiring conductor layers, the arithmetic mean of the surface of the adhesive layer measured by an atomic force microscope The roughness Ra is 0.1 to 1 μm.

According to the adhesive of the present invention, the aromatic / heterocyclic resin-modified product is cross-linked at a high density with a radical polymerizable cross-linking material. It is possible to suppress molecular breakage of the resin-modified product and intrusion of moisture into the resin formed by these, and to provide an adhesive excellent in heat resistance and moisture resistance.

Further, according to the adhesive of the present invention, since the weight average molecular weight is 10,000 to 500,000 and contains a thermoplastic resin which is dissolved in a roughening liquid, the adhesive has excellent stretchability and excellent film formability. And an adhesive capable of forming a rough surface effective for improving the adhesion to the wiring conductor layer on the surface.

Further, according to the adhesive of the present invention, since the glass transition temperature Tg contains an elastomer having a temperature of -60 to -20 ° C., the uncured film has excellent flexibility and is easy to handle. In addition, the cured film can maintain the flexibility at break elongation of 3 to 10% and absorb the stress caused by heat change, and as a result, can provide an adhesive material having good thermal fatigue resistance.

Further, according to the electronic component of the present invention, the arithmetic average roughness Ra of the surface of the adhesive layer measured by an atomic force microscope can be reduced.
Since the thickness is set to 0.1 to 1 μm, the adhesion between the adhesive layer and the wiring conductor layer can be improved and the peel strength can be improved, which is good for reliability tests such as thermal fatigue resistance by TCT and moisture resistance by PCT. An electronic component having a suitable wiring board can be obtained.

[0018]

Next, the adhesive of the present invention and an electronic component using the same will be described in detail. The adhesive of the present invention is a modified aromatic / heterocyclic resin, a radically polymerizable crosslinker, a thermoplastic resin having a weight average molecular weight of 10,000 to 500,000 and being dissolved in a roughening liquid, and a glass transition temperature. T
It is composed of an elastomer having a g of -60 to -20C and a filler.

The adhesive of the present invention may be used in the form of a liquid varnish or a solid film, but is preferably in the form of a film from the viewpoints of surface flatness and easy control of thickness. Here, the film means a thickness of several μm to several tens
It means a thin sheet of about 0 μm.

In the present invention, the aromatic is a carbocyclic compound having a benzene nucleus, and the heterocyclic system is a five-membered ring or a six-membered ring in which a ring is composed of atoms of two or more elements. It is a cyclic compound such as a membered ring, and the aromatic / heterocyclic resin refers to a resin composed of one or a mixture of two or more of the above.

The adhesive of the present invention is obtained by crosslinking a modified aromatic / heterocyclic resin having a rigid molecular structure with a radical polymerizable crosslinking material at a high density.
It is possible to suppress the molecular cleavage of the modified heterocyclic resin and the infiltration of moisture into the modified aromatic / heterocyclic resin, and to provide an adhesive having excellent heat resistance and moisture resistance.

Here, the modified product refers to a product having a radical polymerization functional group such as an allyl group, an acryl group, or a methacryl group. In the present invention, such an aromatic / heterocyclic resin modified product is an allyl-modified resin. Polyphenylene ether, allyl-modified polystyrene, modified norbornene and the like are used.

Further, the adhesive of the present invention is characterized in that a radical polymerizable crosslinking agent is used in an amount of 2 to 10 with respect to the modified aromatic / heterocyclic resin.
% By weight. If the content of the radical polymerizable cross-linking material is less than 2% by weight, it tends to be difficult to cross-link and cure the adhesive while maintaining appropriate flexibility, and if it exceeds 10% by weight, TCT , Etc., tend to be inferior in durability in reliability tests. Therefore, the content of the radical polymerizable cross-linking material is preferably in the range of 2 to 10% by weight.
Such a radical polymerizable cross-linking material may be any monomer that is a low molecular weight compound having a plurality of radical polymerizable functional groups, such as triallyl isocyanurate, divinylbenzene, ethylene glycol dimethacrylate, and diallyl phthalate. Is preferably used. If the reaction temperature is suitable, a radical polymerization initiator such as benzoyl peroxide or lauryl peroxide may be used.The reaction temperature is set in consideration of workability and curing time and resin decomposition. 150-250
C. is preferred.

Further, the adhesive of the present invention has a weight average molecular weight of 10,000 to 500,000 and contains 5 to 30% by weight of a thermoplastic resin soluble in the roughening liquid, based on the modified aromatic / heterocyclic resin. As a result, an adhesive having good stretchability and excellent film moldability can be obtained. If the weight average molecular weight of the thermoplastic resin is less than 10,000, the film tends to become brittle and the moldability deteriorates,
On the other hand, if it exceeds 500,000, the viscosity of the adhesive becomes high, and a film having a uniform thickness tends not to be obtained. Therefore,
The weight average molecular weight of the thermoplastic resin is preferably in the range of 10,000 to 500,000. Further, the content of the thermoplastic resin is 5% by weight.
If the amount is less, the film tends to be brittle and good stretchability cannot be obtained, and if it exceeds 30% by weight, the heat resistance tends to be poor. Therefore, the content of the thermoplastic resin is 5 to
Preferably it is in the range of 30% by weight.

This thermoplastic resin is easily dissolved in a roughening solution such as an aqueous solution of an oxidizing agent such as permanganates or chromates, so that the film is formed into a roughening solution after the film is formed and cured. By dipping, a rough surface having good adhesion to the wiring conductor layer can be easily formed on the film surface. As a roughening liquid, permanganates are generally used because chromates have toxicity.
Particularly, potassium permanganate having a large oxidation number and strong oxidizing power is preferably used.

As such a thermoplastic resin, polyesters such as polyethylene phthalate (PET) and polybutylene phthalate (PBT) / alkyl adipate, and acrylic esters such as polymethyl methacrylate / polybutyl methacrylate are used. .

The adhesive of the present invention contains an elastomer having a glass transition temperature Tg of -60 to -20 ° C in an amount of 10 to 40% by weight based on the modified aromatic / heterocyclic resin. The uncured film has excellent flexibility and is easy to handle. Even after curing, the film has an elongation at break of 3 to 10%, and can maintain the flexibility to absorb the stress caused by a thermal change. , Heat fatigue resistance can be improved. When the glass transition temperature Tg is lower than −60 ° C., the tackiness of the adhesive after drying tends to be large, and the handling of the film tends to be difficult. Elongation tends to be small. Therefore, the glass transition temperature Tg of the elastomer is -60 to -20 ° C.
Is preferably within the range. Further, if the content of the elastomer is less than 10% by weight, flexibility tends to decrease, and if it exceeds 40% by weight, the crosslinking density of the adhesive decreases, and the heat resistance and moisture resistance decrease. Tend to be. Therefore, the content of the elastomer is preferably in the range of 10 to 40% by weight.

Here, the elongation at break after curing refers to the elongation of the film when a film having a thickness of several tens of μm is molded with an adhesive and completely cured, and then pulled at a constant speed until the film breaks. The elongation at break is generally preferably in the range of 3 to 10%, and the elongation at break is preferably 3 to 10%.
If it is less than 10%, the thermal fatigue resistance tends to be inferior, for example, cracks occur in TCT, and if it exceeds 10%, the crosslinking density of the resin tends to be low, and the heat resistance and moisture resistance tend to be inferior.

Examples of such an elastomer include acrylic rubber (ACM), acrylonitrile-butadiene rubber (NBR), styrene-butadiene-styrene triblock elastomer (SBS), styrene-isoprene-
Styrene triblock elastomer (SIS) or the like is used.

Further, the adhesive of the present invention is preferably made of an aromatic
It contains 3 to 10% by weight of a filler based on the modified heterocyclic resin. The filler has a function of increasing the strength of the film. If the content of the filler is less than 3% by weight, the flatness of the film tends to be deteriorated. Workability tends to be poor. Therefore, the filler content is preferably in the range of 3 to 10% by weight.

As such a filler, an insulating fine powder is used, and inorganic powder such as silica, aluminum oxide, aluminum nitride, silicon carbide, calcium titanate, titanium oxide, zeolite, or aramid fiber or carbon fiber. Fibers such as glass fibers are used, the average particle diameter is 20 μm or less from the viewpoint of the moldability of the film, the average particle diameter is 10 μm or less from the viewpoint of the perforation property of the through-hole, and the average is from the viewpoint of the filler filling property. Fine powder having a particle size of 7 μm or less is preferred.

In the present invention, when forming a film, methyl ethyl ketone (MKE) or propylene glycol monomethyl ether acetate (PMA) / dimethylformamide (D) is used to obtain good formability.
A solvent such as MF) may be contained in an amount of 1 to 3% by weight.

Such a film is, for example, aromatic
A liquid varnish is obtained by kneading a mixture obtained by adding a radical polymerizable cross-linking material, a thermoplastic resin, an elastomer, a filler, an additive, and a solvent to the modified heterocyclic resin, and the liquid varnish is placed on a PET release sheet. It is formed by coating and drying at a temperature of 60 to 100 ° C. Further, after the film is dried, a polyethylene protective sheet is laminated on the upper surface of the film, and the film can be easily stored by winding in a roll.
The thickness of this film can be set freely,
From the viewpoint of insulating properties, a thickness in the range of 20 to 100 μm is preferable.

The adhesive layer can be formed on the insulating substrate by pressing the film on a desired insulating substrate using a vacuum laminator and thermosetting in an oven.

Thus, according to the adhesive of the present invention, a rough surface capable of obtaining good adhesion to the wiring conductor layer can be formed on the surface thereof, and the elongation at break after curing is as large as 3 to 10%. It is possible to form an adhesive layer excellent in heat fatigue resistance, heat resistance and moisture resistance.

The adhesive of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the present invention. For example, a hindered phenol-based antioxidant for improving the heat resistance of the above-mentioned adhesive, a lubricant of higher fatty acid ester for further improving the moldability, and for improving the peel strength of the wiring conductor layer. It is also possible to include an electroless plating catalyst or the like.

Next, an electronic component using the adhesive of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view of an essential part showing an example of an electronic component when a semiconductor element is mounted as an electronic element on a wiring board using the adhesive of the present invention. An electronic component including the semiconductor element 3. The wiring substrate 2 mainly includes an insulating substrate 4, an adhesive layer 5, and a wiring conductor layer 6. In the example of FIG.
Shows an example in which three layers 5a, 5b, and 5c are formed on the front surface of the insulating substrate 4 and three layers 5d, 5e, and 5f are formed on the back surface.

The insulating substrate 4 is made of a resin material such as glass fiber, aramid fiber, allyl-modified polyphenylene ether resin, modified norbornene resin, and allyl-modified polystyrene, and functions as a support for the adhesive layer 5.
Wiring conductor layers 6 made of copper, nickel, gold and the like formed on both front and back surfaces of the insulating substrate 4 are electrically connected by through hole conductors 8 formed inside through holes 7 formed by drilling or the like. Note that an internal wiring conductor (not shown) may be formed in an inner layer of the insulating substrate 4.

An adhesive layer 5 formed by using the adhesive of the present invention is formed on both front and back surfaces of the insulating base 4.
The adhesive layer 5 functions as a support for supporting the semiconductor element 3 mounted on the wiring board 2.

The adhesive layer 5 is formed by applying a liquid varnish obtained by kneading a mixture obtained by adding a solvent or the like to the adhesive of the present invention to a PET sheet and drying the varnish to a desired thickness using a roller coater. The film is dried and cured at a temperature of 60 to 100 ° C. to obtain a film, and the film is formed by pressing the film on both the front and back surfaces of the insulating substrate 4 with a vacuum laminator. The surface of the adhesive layer 5 is roughened using a roughening solution to have an arithmetic average roughness Ra of 0.1 by an atomic force microscope.
A rough surface of １1 μm is formed. This is because although the thermoplastic resin in the adhesive is in the uncured state, it is uniformly dissolved in the modified aromatic / heterocyclic resin, but when cured, it is 0.01 to 10μ.
Since the particles are dispersed in the form of fine particles having a size of m, the surface of the adhesive layer 5 from which the thermoplastic resin is dissolved and removed by the roughening liquid is formed as a rough surface by countless fine holes.

Conventionally, in the measurement of surface roughness using a stylus-type surface roughness measuring instrument, a stylus having a diameter of 5 μm is used, and irregularities smaller than 5 μm cannot be measured. The atomic force microscope is capable of three-dimensionally measuring even microscopic irregularities of about several tens of nanometers.
It is possible to measure unevenness of 0.5 μm or less which greatly affects the adhesion between the wiring conductor layer 6 and the wiring conductor layer 6, that is, greatly affects the peel strength.

Since the surface of the adhesive layer 5 has a rough surface having an arithmetic average roughness Ra of 0.1 to 1 μm as measured by an atomic force microscope, the adhesion to the wiring conductor layer 6 is improved. The peel strength can be improved, and the peel strength can be improved for reliability tests such as TCT and PCT. If the arithmetic mean roughness Ra of the surface of the adhesive layer 5 measured by an atomic force microscope is less than 0.1 μm, the adhesive layer 5
There is a tendency that the anchor effect between the wiring conductor layer 6 and the wiring conductor layer 6 becomes small and a sufficient peel strength cannot be obtained. If it exceeds 1 μm, a fine wiring pattern required for the build-up method tends to be unable to be formed. Therefore, the roughness of the surface of the adhesive layer 5 has an arithmetic average roughness Ra measured by an atomic force microscope.
It is preferably in the range of 0.1 to 1 μm.

The surface of the adhesive layer 5 can be roughened, for example, by
The surface of the adhesive layer 5 is coated with about 10 organic solvents such as glycol ether.
% And a solution containing about 1% of alkali such as sodium hydroxide for about 5 minutes to swell the surface of the adhesive layer 5 and then into a solution of about 10% of an oxidizing agent such as permanganate. Ten
Immersion for about 1 minute to dissolve the thermoplastic resin on the surface of the adhesive layer 5, and the surface of the adhesive layer 5 is roughened so that the arithmetic average roughness Ra is 0.1 to 1 μm as measured by an atomic force microscope. And finally immersed in about 5% aqueous solution of sulfuric acid for about 5 minutes,
This is performed by reducing the surface of the adhesive layer 5.

The wiring conductor layer 6 is formed on the surface of the adhesive layer 5 of the electronic component 1 of the present invention. The wiring conductor layer 6 functions as a conductive path for electrically connecting an electronic element such as the semiconductor element 3 to an external electric circuit board (not shown). The electrodes are electrically connected by flip chip connection or the like, and the back side is electrically connected to the wiring conductor of the external electric circuit board via solder or the like.

The wiring conductor layer 6 is formed by a subtractive method, an additive method or the like, and the roughened adhesive material layer 5 is formed.
On the surface, for example, copper is deposited by electroless plating, copper is deposited to a predetermined thickness by electrolytic plating after patterning with a dry film photoresist, and then dry film peeling and etching are performed. It is formed by forming a wiring pattern. The wiring conductor layer 6
Is made of a low-resistance metal such as gold, copper, and nickel, and copper is particularly preferable from the viewpoint of low resistance.

Further, the peel strength of the wiring conductor layer 6 is preferably 0.7 to 1.5 kg / cm from the viewpoint of preventing peeling or disconnection from the adhesive layer 5 in TCT or PCT. When the peel strength is smaller than 0.7 kg / cm, the wiring conductor layer 6 tends to be easily separated from the adhesive layer 5, and when the peel strength exceeds 1.5 kg / cm, the adhesion between the wiring conductor layer 6 and the adhesive layer 5 is increased. When the adhesive layer 5 is stretched due to an excessively strong force, the adhesive layer 5 tends to be easily broken inside the resin. Therefore, the peel strength of the wiring conductor layer 6 is 0.7
It is preferably in the range of 1.5 kg / cm.

The thickness of the wiring conductor layer 6 is preferably 3 μm or more from the viewpoint of transmitting a high-speed signal. In order to prevent large stress from remaining in the layer 6 and to make it difficult for the wiring conductor layer 6 to peel off from the adhesive layer 5, the thickness is preferably 50 μm or less.

The adhesive layer 5 and the wiring conductor layer 6 are
When a plurality of layers are formed on the insulating substrate 4, a plurality of films to be the adhesive layer 5 are formed in advance, and the lamination of the adhesive layer 5 and the formation of the wiring conductor layer 6 may be sequentially performed. .

Further, the plurality of wiring conductor layers 6 are
It is electrically connected by a through conductor 10 formed on the inner peripheral wall of a through hole 9 provided inside.

The through hole 9 may be formed by a method of forming a hole by an exposure and development method, a method of forming a hole by a laser method such as a carbon dioxide gas laser, a YAG laser, or a UV laser. It is preferable to use a carbon dioxide laser that can perform fine processing without depending on the diameter, can freely set the diameter of the through hole in the range of 10 to 200 μm, and has a high processing speed. According to the adhesive of the present invention, since the thermoplastic resin constituting the adhesive has a large weight average molecular weight of 10,000 to 500,000 and a small oxygen index, it is easily decomposed by heat by a laser, and the through-hole 9 is formed. At this time, the residue of the adhesive is
When the wiring conductor layer 6 and the penetrating conductor 10 are formed by plating, they can have excellent electrical characteristics.

The through conductor 10 may be formed by performing plating simultaneously with the wiring conductor layer 6 when the wiring conductor layer 6 is applied by plating. The through conductor 10 may be formed by filling the inside of the through hole 9 with metal by plating, in addition to the one formed by attaching the inner wall surface of the through hole 9 to the inside.

Further, the semiconductor element 3 is connected to the wiring conductor layer 6 formed on the surface of the outermost adhesive layer 5 via a connection member 11 such as solder between the semiconductor element 3 and the wiring conductor layer 6. 6 are electrically connected to each other and the semiconductor element 3
The semiconductor element 3 is firmly fixed to the surface of the adhesive layer 5 by injecting an underfill 12 made of resin between the semiconductor device 3 and the adhesive layer 5.

Thus, according to the electronic component of the present invention, the adhesion between the adhesive layer and the wiring conductor layer is improved and the peel strength is improved, and the durability and excellent durability against reliability tests such as TCT and PCT are achieved. An electronic component having reliability can be obtained.

The electronic component of the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention. For example, in the above-described embodiment, three adhesive layers 5
The wiring board 2 was manufactured by laminating
One, two, or four or more adhesive layers may be laminated. Further, the adhesive layer 5 is formed only on the front surface or the back surface.
May be laminated. Further, in order to enhance the adhesion between the via-hole conductor 10 and the adhesive layer 5, it is possible to fill the inside of the through hole 9 with a resin such as the adhesive of the present invention.

[0056]

EXAMPLES In order to evaluate the characteristics of the adhesive of the present invention and the electronic component using the adhesive, an electronic component using the following adhesive film was manufactured.

[Example 1 of Adhesive] Allyl-modified polyphenylene ether was used as an aromatic / heterocyclic resin-modified product, and triallyl isocyanurate was used as a radical polymerizable cross-linking agent for the allyl-modified polyphenylene ether.
10% by weight, 1% by weight of benzoyl peroxide as a radical polymerization initiator, 20% by weight of propionate adipate having a weight average molecular weight of 120,000 as a thermoplastic resin, and an acrylic rubber having a glass transition temperature Tg of -30 ° C. as an elastomer. 20% by weight, 8% by weight of finely divided silica as a filler and heated toluene as a solvent were added and mixed to prepare a varnish-like adhesive.

The varnish-like adhesive was applied on a PET sheet by a roller coater so that the thickness after drying became 45 μm, and then dried at a temperature of 60 to 100 ° C. to form an adhesive film (adhesive film A). Obtained. The uncured adhesive film A was subjected to a 180-degree bending test for flexibility evaluation, but no abnormality such as cracks was observed in the bent portion.

After the adhesive film A was dried and cured at a temperature of 200 ° C. for 3 hours, the elongation at break was 8% when the film was pulled at a rate of 5 mm / minute by a tensile measuring machine.
Further, when a heat history of 100 hours was added at a temperature of 150 ° C., the elongation at break was 9%.

[Example 2 of Adhesive] A modified norbornene resin was used as a modified aromatic / heterocyclic resin, and ethylene glycol dimethacrylate was used as a radical polymerizable cross-linking agent in the modified norbornene resin at 5% by weight. 30% by weight of butylene adipate having a weight average molecular weight of 200,000 as a plastic resin, 20% by weight of epoxidized NBR having a glass transition temperature Tg of -60 ° C. as an elastomer, 4% by weight of finely divided silica as a filler, and PM as a solvent
A was added and mixed to produce a varnish-like adhesive.

The varnish-like adhesive is applied on a PET sheet by a roller coater so that the thickness after drying becomes 30 μm, and then dried at a temperature of 60 to 100 ° C. to form an adhesive film (adhesive film B). Obtained. The uncured adhesive film B was subjected to a 180-degree bending test for flexibility evaluation, but no abnormality such as a crack was observed in the bent portion.

After the adhesive film B was dried and cured at a temperature of 180 ° C. for 3 hours, the elongation at break was 9% when the film was pulled at a rate of 5 mm / minute by a tensile measuring machine.
Further, when a heat history of 100 hours was added at a temperature of 150 ° C., the elongation at break was the same as 9%.

Comparative Example of Adhesive Material 10% by weight of styrene monomer, 1% by weight of benzoyl peroxide, 1% by weight of benzoyl peroxide, 30% by weight of finely divided silica as a filler, and toluene as a solvent were added to a thermoplastic norbornene resin. A varnish-like adhesive was produced by mixing.

The varnish-like adhesive was applied on a PET sheet by a roller coater so that the thickness after drying was 45 μm, and then dried at a temperature of 60 to 100 ° C. to form an adhesive film (adhesive film C). Obtained. When the uncured adhesive film C was subjected to a 180-degree bending test for flexibility evaluation, cracks occurred at the bent portions.

After the adhesive film C was dried and cured at a temperature of 150 ° C. for 1 hour, the elongation at break was 2% when the film was pulled at a rate of 5 mm / minute by a tensile tester. In addition, 15
When a heat history of 100 hours was added at a temperature of 0 ° C., the elongation at break was 1%.

As described above, it was confirmed that the film produced using the adhesive of the present invention had excellent flexibility when uncured, and a good elongation at break of 8 to 9% after curing. Was.

[Embodiment 1 of Electronic Components] An adhesive film A was simultaneously laminated on both front and back surfaces of an insulating substrate made of glass fiber and allyl-modified polyphenylene ether resin by a vacuum laminator.
After the T film was peeled off and cured at a temperature of 200 ° C. for 1 hour, a through hole 9 was formed by a carbon dioxide laser. Next, the surface roughness Ra of the film surface was measured with an atomic force microscope, and the film was roughened with a potassium permanganate solution so that the arithmetic average roughness Ra was 0.5 μm. Thereafter, after treatment with a palladium-based plating catalyst, electroless copper plating was performed, then wiring pattern processing was performed with a dry film photoresist, and a wiring conductor layer 6 having a thickness of 18 μm was formed by electrolytic copper plating. At that time, the peel strength of the wiring conductor layer 6 was 0.8 kg / cm. Further, heat treatment was performed at a temperature of 200 ° C. for 2 hours to stabilize the peel strength. After that, the lamination of the adhesive film A and the formation of the wiring conductor layer 6 and the through conductor 10 by drilling, roughening, and plating of the through holes 9 are repeated a plurality of times to form the six adhesive layers 5 and the wiring conductor layers 6
Was formed on the insulating substrate 4, nickel / gold plating was performed on the pads subjected to the solder resist processing, and further, solder bumps were formed. Then, after mounting the semiconductor element 3 on the solder bumps of the wiring board 2 and performing reflow electrical connection, an underfill 12 material is injected into a gap between the semiconductor element 3 and the wiring board 2 to obtain a sample for a reliability test. Using this sample, a temperature cycle test (TCT) and a pressure cooker test (PCT) were performed as reliability tests, and the electronic components were evaluated based on the appearance of the wiring board such as cracks, swelling and peeling, and the rate of change in resistance. Was evaluated.

The TCT was performed using a gas phase cooling / heating tester, and the sample was left in a gas phase at a temperature of −55 ° C. and 125 ° C. for 30 minutes each, and this was performed as one cycle under the conditions of 1000 cycles. The resistance value before the test and the resistance value after the test were measured and calculated.

In the PCT, a temperature variable life tester was used, and a sample was prepared at a temperature of 121 ° C., a relative humidity of 100%, and a pressure of 2.1 ×.
The test was left for 168 hours under the condition of 105 Pa, and the resistance change rate was calculated by measuring the resistance value before the test and the resistance value after the test.

As a result, the electronic component 1 of the present invention
No cracks occurred even after 1000 cycles, and the resistance value change rate was as low as 5%. Further, even after 168 hours of PCT, there was no swelling or peeling, and the rate of change in resistance was as low as 7%.

[Embodiment 2 of Electronic Parts] After an adhesive film B was simultaneously laminated on both front and back surfaces of an insulating substrate made of glass fiber and allyl-modified polyphenylene ether resin by a vacuum laminator, the PET film was peeled off.
After curing at a temperature of 180 ° C. for 1 hour, a through hole 9 was formed by a carbon dioxide laser. Next, the surface roughness of the film surface was measured with an atomic force microscope, and the arithmetic average roughness Ra was 0.9 μm.
m was roughened with potassium permanganate.
Further, after the above wiring board 2 is treated with a palladium-based plating catalyst, electroless copper plating is performed, then wiring pattern processing is performed with a dry film photoresist, and a 20 μm thick wiring conductor layer is formed by electrolytic copper plating. 6 was formed. At this time, the peel strength of the wiring conductor layer 6 was 1.0 kg / cm. Further, heat treatment was performed at a temperature of 180 ° C. for 2 hours to stabilize the peel strength. Next, the lamination of the adhesive material film 2 and the formation of the wiring conductor layer 6 and the through conductor 10 by drilling, roughening, and plating of the through hole 9 are repeated a plurality of times.
After the adhesive layer 5 and the wiring conductor layer 6 are formed on the insulating substrate 2, nickel / nickel
Gold plating was performed, and further, solder bumps were formed.

After mounting the semiconductor element 3 on the solder bumps of the wiring board 2 thus obtained and performing reflow electrical connection, an underfill 12 is injected into a gap between the semiconductor element 3 and the wiring board 2 to perform a reliability test. A sample was obtained.

Using this sample, the same TCT and PCT as in the reliability test (Embodiment 1 of the electronic component) were performed, and the appearance of the wiring board 2 such as cracks, swelling and peeling, and the value of the rate of change in resistance were determined. evaluated.

As a result, no cracks occurred in the sample even after 1000 TCT cycles, and the resistance change rate of the wiring conductor layer 6 was a low value of 6%. Further, even after 168 hours of PCT, there was no swelling or peeling, and the rate of change in resistance of the wiring conductor layer 6 was a low value of 8%.

[Comparative Example 1 of Electronic Parts] After an adhesive film C was simultaneously laminated on both front and back surfaces of an insulating substrate made of glass fiber and allyl-modified polyphenylene ether resin by a vacuum laminator, the PET film was peeled off.
After curing at a temperature of 150 ° C. for 1 hour, a through-hole was formed with a carbon dioxide laser. Next, the surface of the adhesive layer was roughened with an oxidizing agent such as potassium permanganate so that the arithmetic average roughness Ra measured by an atomic force microscope was 0.05 μm. After that, after treatment with a palladium-based plating catalyst, electroless copper plating is performed, and then wiring pattern processing is performed with a dry film photoresist, and a thickness of 18 μm is formed by electrolytic copper plating.
m wiring conductor layers were formed. The peel strength of the wiring conductor layer at that time was 0.7 kg / cm. In addition, heat treatment was performed at 150 ° C. for 2 hours to stabilize the peel strength. Next, the lamination of the adhesive film C and the drilling / roughening / plating of the through-holes were repeated a plurality of times to form six adhesive layers / wiring conductor layers on the insulating substrate, followed by solder resist processing. The pads were plated with nickel and gold, and solder bumps were formed.

After mounting the semiconductor element on the solder bumps of the wiring board thus obtained and performing reflow electrical connection, an underfill is injected into a gap between the semiconductor element and the wiring board to form an electronic component for reliability test. A sample for comparison was obtained.

Using this comparative sample, the same TCT and PCT as in Example 1 of the electronic component were performed as a reliability test. As a result, a crack occurred in the comparative sample after 200 cycles of TCT. Later blistering occurred.

[0078]

According to the adhesive of the present invention, a modified aromatic / heterocyclic resin is cross-linked at a high density with a radical polymerizable cross-linking material. It is possible to suppress the molecular breakage of the modified product and the intrusion of moisture into the modified aromatic / heterocyclic resin, and to provide an adhesive material having excellent heat resistance and moisture resistance.

The adhesive of the present invention has a weight average molecular weight of 10,000 to 500,000 and contains a thermoplastic resin which is soluble in a roughening liquid. And an adhesive capable of forming a rough surface effective for improving the adhesion to the wiring conductor layer on the surface.

Further, since the adhesive of the present invention contains an elastomer having a glass transition temperature Tg of −60 to −20 ° C., the uncured film is excellent in flexibility and easy to handle. In addition, the cured film can maintain the flexibility at break elongation of 3 to 10% and absorb the stress caused by heat change, and as a result, can provide an adhesive material having good thermal fatigue resistance.

Further, according to the electronic component of the present invention, the arithmetic mean roughness Ra of the surface of the adhesive layer measured by an atomic force microscope is calculated as follows.
Since the thickness is set to 0.1 to 1 μm, the adhesion between the adhesive layer and the wiring conductor layer can be improved and the peel strength can be improved, which is good for reliability tests such as thermal fatigue resistance by TCT and moisture resistance by PCT. An electronic component having a suitable wiring board can be obtained.

[Brief description of the drawings]

FIG. 1 is a main part sectional view showing an example of an electronic component when a semiconductor element is mounted as an electronic element on a wiring board using the adhesive of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electronic component 2 ... Wiring board 3 ... Semiconductor element 4 ... Insulating substrate 5 ... Adhesive layer 6 ...・ ・ ・ Wiring conductor layer 7 ・ ・ ・ ・ ・ ・ Through hole 8 ・ ・ ・ ・ ・ ・ Through hole conductor 9 ・ ・ ・ ・ ・ ・ Through hole 10 ・ ・ ・ ・ ・ ・ Through conductor 11 ・ ・ ・ ・ ・ ・Connection member 12 ... Underfill

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 23/14 H05K 3/38 E H05K 3/38 H01L 23/14 RF term (Reference) 4J004 AA01 AA02 AA05 AA10 AA15 AA16 AA17 AA18 BA02 FA05 4J011 PA54 PA65 PA69 PA76 PA79 PA88 PB40 PC02 4J027 AA08 AH03 BA18 BA20 BA22 BA29 CB04 CD09 4J040 CA072 DF042 DF052 DM012 ED042 ED052 EG022 FA042 HA072 FA042 FA0714 KA16 KA42 LA01 LA02 LA06 LA07 LA08 LA09 MA02 MB05 NA20 5E343 AA02 AA07 AA12 AA36 BB05 BB22 CC01 CC02 CC07 CC23 CC43 CC50 DD33 DD43 EE21 EE37 GG01

Claims (5)

[Claims] 1. A modified aromatic / heterocyclic resin, a radical polymerizable crosslinker, and a weight average molecular weight of 10,000 to 5
A thermoplastic resin which is 00000 and is dissolved in the roughening liquid,
It consists of an elastomer having a glass transition temperature Tg of −60 to −20 ° C. and a filler, and has an elongation at break of 3 to 10 after curing.
%. 2. The radically polymerizable cross-linking material is 2 to 10% by weight, the thermoplastic resin is 5 to 30% by weight, and the elastomer is 10 to 40% by weight of the modified aromatic / heterocyclic resin. The adhesive according to claim 1, wherein the filler is contained in an amount of 3 to 10% by weight. 3. The adhesive according to claim 1, wherein the adhesive is in the form of a film. 4. An insulating substrate, an adhesive layer formed on the insulating substrate by using the adhesive according to claim 1, and each of the insulating substrate and the adhesive layer An electronic element is mounted on a wiring board comprising: a plurality of wiring conductor layers formed on the surface; and a through conductor formed inside a through hole formed in the adhesive layer and electrically connecting the plurality of wiring conductor layers. Wherein the arithmetic average roughness Ra of the surface of the adhesive layer measured by an atomic force microscope is 0.1.
An electronic component having a thickness of 1 μm to 1 μm. 5. The electronic component according to claim 4, wherein the peel strength of the wiring conductor layer formed on the surface of the adhesive layer is 0.7 to 1.5 kg / cm.